How to check if date is at least previous day? - ios

Question

Hi everyone I'm trying to get a positive answer when comparing a date earlier than today
To do this I am using a Date extension with this boolean
extension Date {
var isPreviousDate: Bool {
return self.timeIntervalSinceNow.sign == .minus
}
}
Here is my problem .. when I print the date to compare it tells me that today's date is earlier and I don't understand why
Since I'm having problems I tried to create a current date and compare it with today's date the answer is that today's date is earlier than today ... this is weird because it shouldn't tell me it's older
This is how I create the date to compare
var calendar = Calendar(identifier: Calendar.current.identifier)
calendar.timeZone = NSTimeZone(name: "UTC")! as TimeZone
guard let selectedDate = calendar.date(from: DateComponents(year: Date().currentYear, month: Date().currentMonth, day: Date().currentDate)) else { return }
print("isPrevious Date :",selectedDate.isPreviousDate)
print(selectedDate)
am I doing something wrong?
this is what I read in the console when I print the created date to compare
isPrevious Date: true
2021-02-11 00:00:00 +0000

Answer 1

timeIntervalSinceNow is a FloatingPoint value with a very high precision, that represents seconds passed since the Date.
To check if current date is at least on a previous day, you could do something like this:
extension Date {
var isAtLeastPreviousDay: Bool {
return isPast && !isToday
}
private var isPast: Bool {
return self < Date()
}
private var isToday: Bool {
return Calendar.current.isDateInToday(self)
}
}

Answer 2

The issue there is that you are using a custom calendar using UTC timezone. You should use the current calendar with the current timezone. Note that you can use Calendar method startOfDay to get the start of day of a specific date:
extension Date {
var isPreviousDate: Bool {
timeIntervalSinceNow.sign == .minus
}
var startOfDay: Date {
Calendar.current.startOfDay(for: self)
}
}
let now = Date()
let startOfDay = now.startOfDay
print("isPrevious Date:", startOfDay.isPreviousDate) // true
If you would like to check if a date is in yesterday all you need is to use calendar method isDateInYesterday:
extension Date {
var isDateInYesterday: Bool {
Calendar.current.isDateInYesterday(self)
}
}
Date().isDateInYesterday // false
Date(timeIntervalSinceNow: -3600*24).isDateInYesterday // true